Aggregate is the basic material used in construction, including sand, gravel, crushed stone, slag, and recycled concrete. Aggregates are a basic resource, and are necessary for modern construction. Aggregates are the basic input materials for concrete and asphalt as well as base materials used under foundations and roads.
Aggregate is provided through the use of quarries, which are present throughout the world, and which require bedrock deposits of aggregate quality. Large quarry with sand and gravel operations exist near virtually all population centers. These are capital-intensive operations, utilizing large earth-moving equipment, belt conveyors, and machines specifically designed for crushing and separating various sizes of aggregate to create distinct product stockpiles.
Aggregate is needed for any kind of construction. Roads require aggregate for continual maintenance and rebuilding. Homes, offices, warehouses, shopping centers, and workplaces all require foundations composed of aggregate, as well as concrete footers, asphalt parking lots, manufactured bricks, blocks and poured walls.
The aggregate industry requires access to water, and frequently adds large amounts of sediment to such water. This can raise environmental concerns, particularly when the aggregate producer is located in, or near to, a residential area.
In the prior art, flocculants have been used within the water to bind the sediment, which can then be filtered, allowing the filtered water to be placed back into the environment. Flocculants, or flocculating agents, are chemicals that are used to promote flocculation by causing colloids and other suspended particles in liquids to aggregate, forming a floc. Flocculants are used in water treatment processes to improve the sedimentation or filterability of small particles. For example, a flocculent may be used in water filtration to aid removal of microscopic particles which would otherwise cause the water to be cloudy and which would be difficult or impossible to remove by filtration alone.
Many flocculants are multivalent cations such as aluminum, iron, calcium or magnesium. These positively charged molecules interact with negatively charged particles and molecules to reduce the barriers to aggregation. In addition, many of these chemicals, under appropriate pH and other conditions, react with water to form insoluble hydroxides which, upon precipitating, link together to form long chains or meshes, physically trapping small particles into a larger floc. Other factors such as pH, temperature, and salinity can induce flocculation or influence flocculation rates.
A typical embodiment of a prior art water management system is shown in FIG. 1. In such a system a series of source and settling ponds are linked together by gravity feed culverts or pumps.
With reference to FIG. 1, a prior art water management system may operate as follows:                1. First and second settling ponds 10, 15, serve as a final step for sediment control before the water is discharged into the nearby river 20.        2. Sediment is cleaned out of the first and second settling ponds 10, 15 into adjacent first and second silt ponds 25, 30, respectively, where the sediment is left to dry before being hauled to a first pit 35, which is typically located offsite.        3. First and second settling ponds 10, 15 are balanced by a connecting culvert 65. Pump storage facility 40 located between first and second settling ponds 10, 15, recycles water from second settling pond 15 to second source pond 55.        4. Second and third source ponds 55, 60 are balanced by a connecting culvert 70. Source water from second source pond 55 is pumped to first source pond 52 when needed or otherwise pumped to the aggregate site for dust control.        5. First source pond 52 provides water to the various pieces of operation equipment at the aggregate site, including a coarse aggregate washer, and/or sand plant.        6. Fourth settling pond 90, the first stage of settling, receives water from the washer, sand plant, and run-off from the aggregate pit 85        7. Third settling pond 80 is gravity fed from fourth settling pond 90.        8. Sediment is cleaned out of third and fourth settling ponds 80, 90 regularly into fourth silt pond 95. Once the silt is dry (which may take up to 6 months) the silt is hauled off to first pit 35.        9. Fourth settling pond 90 receives clean water skimmed off the top of fourth silt pond 95.        10. Third settling pond 80 is retained all day before being sent across in the afternoon through pipe 100 passing under road 95 to second settling pond 15 for retention. Steps 1 through 10 are then repeated.        
While the above detention/retention water management system may do an adequate job of preventing overflow from entering river 20, it may not be capable of handling severe storm conditions. Such conditions provide severe storm-water diversions to the system. These storm-water diversions overtax the capacity of the system resulting in discolored water being discharged into river 20. Another disadvantage is that the system of ponds requires a significant amount of space, time and maintenance for its upkeep and operation. For example, maintenance of the system requires front-end loaders to regularly clean pond mud out settling ponds 10, 15, 80, 90 as well as gravel trucks to haul the silt offsite. Also, it is estimated that the ponds take up approximately 1600 m2 of space that could be used otherwise. This consumption of time, space and money along with the potential threat, in severe storm conditions, of endangering river 20, suggests a need for alternatives for dealing with the gravel pit water issues.